The present invention relates to an improved blowout preventer and particularly to an improved blowout preventer in which a portion of the packer which is subject to the most wear may be easily and quickly replaced.
Prior to the present invention blowout preventers have long had rams which carried a packing element on their front face which is adapted to seal against both the face of the opposite packer and around a string positioned in the recesses of the opposed packers.
U.S. Pat. No. 4,541,639 discloses a ram-type blowout preventer with a ram front packer which is replaceable. In one form of this prior patent, the replaceable portion of the ram front packer extends completely across the front of the packer and in another form the replacement form of the packer extends immediately around the pipe engaging recess of the packer. In both forms the packer and the insert have interengaging elements which retain the insert in the front face of the packer. The insert element of both forms included both upper and lower retaining plates having the same shape as the insert and bonded thereto so that the complete assembly could be removed and a new insert inserted into the main body of the packer.